1. Field of the Invention
The present invention relates to an IC testing apparatus for testing one or more semiconductor integrated circuit devices and other various electric devices (hereinafter referred to as an "IC" or "ICs" to represent them), more particularly relates to an IC testing apparatus which excels in attaining a uniformity of a pressing force against a contact portion of an IC to be tested.
2. Description of the Related Art
An IC testing apparatus called a "handler" conveys a large number of ICs held on a tray to the inside of a testing apparatus where the ICs are made to electrically contact a test head, then the IC testing unit is made to perform the test. When the test is ended, the ICs are conveyed out from the test head and reloaded on trays in accordance with the results of the tests so as to sort them into categories of good ICs and defective ones, etc.
In an IC testing apparatus of the related art, the trays for holding the DUTs (Devices under test) to be tested or the tested DUTs (hereinafter referred to as "customer trays") and the trays conveyed circulated inside the IC testing apparatus (hereinafter referred to as the "test trays") are different in type. In this type of IC testing apparatus, the ICs are switched between the customer trays and the test trays before and after the test. In the test process where the ICs are tested by being brought into contact with the test head, the ICs are pushed against the test head in the state held on the test trays.
In test processing of an IC testing apparatus of the related art, an IC to be tested is pressed against contact pins by lowering a press mechanism called pusher. The lowering limit of the pusher is decided by a stopper which makes the distance between the pusher and the contact portion a predetermined distance.
However, there exists not a small production error between a thickness of an IC to be tested itself (the error is defined as .DELTA.X), a production dimension of the stopper on the pusher side and the pusher surface (the error is defined as .DELTA.Y), and a production dimension of the stopper on the contact portion side and tips of the contact pins (the error is defined as .DELTA.Z), and the multiplied amount of .DELTA.X to .DELTA.Z normally becomes as much as about .+-.0.1 to .+-.0.2 mm.
Therefore, when the multiplied error of .DELTA.X to .DELTA.Z becomes, for example, +0.04 mm, as shown in a pusher stroke-load curve in FIG. 13, a load of 45 gf/1 ball is actually acted on the IC to be tested for the reference load of 25 gf/1 ball (in this case, it is sufficient if the pusher stroke is set at 0.18 mm). This causes a fear that the IC is damaged or broken. Contrary to this, when the multiplied error of .DELTA.X to .DELTA.Z varies, for example, by -0.1 mm to the minimum side, it is liable that a sufficient press force cannot be obtained and the test cannot be carried out.
Though the total error can be reduced by improving respective dimension precision of the pusher and the contact portion, there is a certain limit to attaining such dimension precision. Moreover, since dimension precision of a package mold is quite rough in chip size packages (CSP), etc., the production error .DELTA.X becomes large when an IC to be tested is a CSP chip. Therefore, only attaining higher precision of the pusher and contact portion is not enough as a countermeasure.